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Subject: Animation LFO (was: Mock up the MOTM-390 uLFO)

From: jhaible@...
Date: 2001-12-05

IMO, the uLFO should not be a scaled down version
of the big one, but something to complement it.

So here's a completely different idea:

What about an "Animation LFO" ?
To breathe life into static patches, you need a lot of
subtle modulation rather than the most exciting of
waveshapes.

In the JH-3, I have a module that consists of five
triangle-only LFOs (independend frequency control).
And it has an extra output where all LFOs are
added which are not used on their individual outputs.

The idea behind this was to have either
(1) a bank of simple, independent LFOs to modulate
various destinations sat different rates, or
(2) to have a "pseudo random" waveform from adding
several LFO outputs. This is very useful as a
non-periodic modulation source that doesn't
make unexpected "jumps" like filtered random signals.
(3) A mix of both.

Translated to MOTM, this could be:

4 triangle LFOs in one module.
4 Pots for Frequency of each LFO
4 Output jacks with a clever assignment:

Outputs 1 ... 3 carry LFO outputs 1 ...3.
Output 4 carries the weighted sum of all otherwise
unused LFOs, including LFO 4.

This means:

If all jacks are used, you have 4 independent LFOs.

If you only plug in output 4, you have
(LFO1+LFO2+LFO3+LFO4)/4 at output 4. (This is is much better
fluctuating voltage source than Buchla's infamous
Source Of Uncertainty, IMHO)

If you plug in output 1 and 4, you have LFO 1 at output 1
(of course), and still (LFO2+LFO3+LFO4)/3 at output 4.

If you plug in output 2, 3 and 4, you have
LFO2 at output 2, LFO3 at output 3, and
(LFO1+LFO4)/2 at output 4

Complicated? No. Each unused output is simply propagated
to Output 4, and the volatge swing there is constant at +/-5V.

If you have tried this once, you never want to miss it again.
You can even do some crude "Fourier Shaping" of the waveform
at output 4 when you set integer ratios for the LFO Rates.
(Integer ratios will only be approximated -> animated
waveforms ... No integer ratios: Pseudo random ...)

JH.